Generally speaking, a roller board is configured for a user to ride on a board with wheels at the front and rear sides, respectively, and to move forward while kicking the ground with one foot.
The above mentioned roller board is widely used because it is portable and is easy to store and anyone can easily use it.
However, since the conventional roller board is driven with one foot kicking the ground, a kid or a child whose physical frame is not fully grown might suffer from the deformed physical growths, and when a user uses it for a long time, a lot of physical energy is consumed. In particular, when it is used on a slope, more energy is needed, so there are lots problems to use it for a long time and to enjoy with it.